The present invention relates to ultrasonic drilling apparatus for highly efficient and precision use, such as medical and dental surgery. The present invention also relates to suturing devices for the medical field.
Dental and surgical procedures involving the use of an ultrasonic probe for removing tissue or for drilling are well known. For example, in dentistry various ultrasonic probes having operative tips that are caused to vibrate at a frequency of about 30,000 Hz are applied to the teeth and vibrated to remove scale and plaque from tooth surfaces. Ultrasonic probes are also used during cataract lens eye surgery to efficiently remove the cataract lens from the eye. Moreover, various surgical procedures make use of a ultrasonic probe for use in drilling holes through bone. Surgical procedures typically make use of various ultrasonic probes having operative tips that are caused to vibrate at frequencies between 20,000 Hz and 60,000 Hz with a stroke of about 20 xcexcm to 150 xcexcm depending on the medical purpose.
Meanwhile, health practitioners frequently use sutures to close various openings such as cuts, punctures, and incisions in various places in the human body. Sutures are also used to join two body parts together by attaching a suture to a first internal body part and then securing the suture to another body part. For example, reattachment of a rotator-cup tendon requires that a suture be passed through a detached tendon and then secured to a hole or anchor in a bone.
Sewing of sutures has been done previously by physicians with devices such as mandibular awls and J-hooks. A J-hook is a suture tool having a longitudinally extending handle, a stem projecting from the handle, and a hook projecting in the plane perpendicular to the axis of the handle and stem. The hook is rotated to push or pull the suture through a hole in the body tissue. Unfortunately, a J-hook tool cannot be used in connection with suturing through holes drilled in bone by prior art ultrasonic probes as the arc shaped end of the J-hook is incapable of projecting through the straight bore drilled by an ultrasonic probe.
It would thus be desirable to have an ultrasonic drilling device that drilled arced shapes through hard materials such as bone for medical procedures. It would also be desirable to provide an ultrasonic drill which was capable of drilling arced shapes through other hard materials such as boron carbide, glass, titanium carbide, steel and the like.
Briefly, in accordance with the invention, we provide an xe2x80x9cultrasonic suture devicexe2x80x9d capable of drilling arc shapes through hard materials. The ultrasonic suture device includes a piezoelectric transducer for converting an externally supplied electrical wave to an ultrasonic mechanical wave producing a mechanical longitudinal stroke. The ultrasonic suture device further includes a horn adjacent to the piezoelectric transducer. Either an exponential horn or stepped horn can be used depending on the device""s purpose. The elongate horn has a proximal end and a distal end. The proximal end is positioned adjacent to the transducer, while the distal end forms an operative tip. The length of the elongate horn is determined by the equation (xcex/2)n, where xcex=wavelength and n=1, 2, 3, 4 . . . , to bring a nodal point to the distal end of the horn.
Attached to the distal end of the elongate horn is a probe. The probe includes a stem section which extends along a first axis. The probe further includes an extension section and an arc section. The arc section is semicircular in construction and positioned in the plane perpendicular to the stem""s axis. Meanwhile, the extension section connects the stem section of the probe with the arc section of the probe. Preferably, the extension section first projects outwardly from the stem section""s axis to define a first segment. Thereafter, the extension section transitions so as to have a small spiral segment in the plane perpendicular to the stem section""s axis. Extending from the distal extremity of the extension section""s spiral segment is the probe""s arc section. Preferably, the arc section of the probe is semicircular in construction and also constructed in the plane perpendicular to the stem""s axis. The length of the probe is determined by the equation xcex(2n+1)/4, where xcex=wavelength, and n=1, 2, 3 . . . to bring the maximum amplitude of the stroke to the distal end of probe.
In a preferred embodiment, the length of the ultrasonic suture device""s elements are constructed dependant upon the wavelength (xcex) produced by the transducer so that the sum of the lengths of the horn and probe is evenly divisible by xc2xcxcex., but not evenly divisible by xc2xdxcex according to the equation (xcex/2)n+xcex(2n+1)/4 so that the maximum amplitude of the wave produced by the transducer is provided at the distal end of the probe. For example, in a preferred embodiment, the horn is one-half(xc2xd) xcex in length, the stem section is one-half(xc2xd) xcex in length, the first segment of the extension section is one-eighth (xe2x85x9) xcex in length, the second spiral segment of the extension section is one-eighth (xe2x85x9) xcex in length, and the length of the arc section is one-half (xe2x85x9) xcex. As described, the sum of the lengths of the horn and probe is {fraction (7/4)}xcex, and thus evenly divisible by xc2xcxcex but not xc2xdxcex. As understood by those skilled in the art the length is constructed to produce maximum vibration at the tip of the probe as maximum vibration is found at increments of one-half (xc2xd) xcex along the length of the probe from the point xc2xcxcex after the first nodal point after the transducer.
The wavelength is dependent on the frequency of the transducer and the velocity of the wave through the horn and probe. The transducer may produce any frequency for purposes of the present invention, though common ultrasonic frequencies of 20-60 kHz are considered preferable. The speed that the wave travels through the ultrasonic suture device will vary depending on the construction and materials used for the horn and probe. However, it has been found that if medical grade stainless steel is used, the wave speed through the device is approximately 5-6,000 m/second, and stainless steel SS316 has a velocity of 6,000 m/second. By using relatively simple mathematics, one skilled in the art can determine the wave length of the ultrasonic suture device by knowing the frequency of the device""s transducer. For example, where a preferred ultrasonic suture device employs a stainless steel SS316 horn and probe, and a transducer producing 40 kHz, the wave length is equal to 6,000 m/second÷40 kHz (waves/second)=150 mm. Thus, the preferred ultrasonic suture device described above, having a transducer producing 40 kHz and having a horn and probe constructed of stainless steel SS316, has a horn length of 75 mm, and a probe having a stem length of 75 mm, a first extension segment of 18.75 mm, a second spiral extension segment of 18.75 mm, and an arc section having a length of 75 mm. Of course, the frequency of the transducer, material and the lengths of individual components may be altered by those skilled in the art without departing from the spirit and scope of the invention.
In operation, a person attempting to create an arc shaped bore in a hard material places the probe""s tip adjacent to the hard material""s exterior surface. The probe is then rotated about the stem section""s axis so that the tip projects into the hard material along the arced path created by the arced construction of the arc section of the probe. The energy produced by the transducer is amplified by the horn and transmitted to the device""s tip causing an arc shaped bore to be formed in the hard material as the probe is rotated.
The probe and arc section of the probe may be rotated by manually rotating the transducer, horn and probe with one""s hands. Alternatively, the ultrasonic suture device of the present invention may include a construction wherein the transducer and horn are rotatably affixed within a housing as described in U.S. Pat. No. 6,204,592 which is incorporated by reference herein. The housing includes a separate electrical motor electrically coupled to a control system for controllably rotating the transducer and horn within the housing. Selective activation of the motor causes the transducer and horn to rotate within the housing, thereby causing the probe to rotate relative to the stem""s axis.
Accordingly, it is a principal object of the invention to provide an ultrasonic device capable of producing arc shaped bores through hard materials.
It is still another object of the invention to provide an ultrasonic suture device for producing arc shaped bores through bone capable of being used in connection with suturing procedures.
These and other, further and more specific objects and advantages of the invention will be apparent to those skilled in the art from the following detailed description taken in conjunction with the drawings.